Underwater propulsion system



' Feb. 7, 1967 J, D. RocKENFr-:LLER 3,302,401

UNDERWATER PROPULSION SYSTEM 2 Sheets-Sheet 1 Filed Jan. 26, 1965 14.1 l l l I l l l I I l I |4| l l I Ill .l l l 2 I III wz Qzo :IV m u u n @y1 .PN Nm. f QN 1 l" lv mw mm mugs 11V w Q 55 335mm 2m: x m T 1 R I m\ m, EMME: Qwmod m Qm @i Al w ma Wm. o o o o o o o E 11V v. I| :Erm mw, :wwm wpl m\ @Ekmwmwm E ...E mwmwy m# .m @A L T/h N F WM W E M 0^ D. M

H TTORN E YS Feb. 7, 1967 J. D. ROCKENFELLER UNDERWATER PRoPULsIoN SYSTEM 2 Sheets-Sheet 2 Filed Jan. 26, 1965 mmml l l l l l l l I l [Illllllisl l l||| um, o o o 4o o o o V f mmz www L JP INVENTOR. JZJHA/ D. /QQCKENFELLEQ H TTOPNEYS United States Patent O 3,302,401 UNDERWATER PROPULSION SYSTEM John D. Rockenfeller, Rockville, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed Jan. 26, 1965, Ser. No. 428,131 V Claims. (Cl. 6050) My invention relates to underwater propulsion systems and more particularly to those capable of operating at great depths. Some underwater propulsion systems of the prior art employ chemical energy in the form of a fueloxidizer combination, the reaction products of which are gaseous. Such systems are especially undesirable for torpedoes and submarines since a visible wake is created by the trail of gas bubbles. Furthermore, at the extreme depths achieved by bathyscaphes, the generation of gaseous exhaust products will either seriously impair efficiency or render the propulsion system inoperative due to the losses incurred in pumping large volumes through high pressure differentials.

Other propulsion systems of the prior art employ batteries. These have the advantage that no gaseous exi haust wake is generated; and no pumping losses associated with gaseous exhausts are incurred. However, the energy-to-weight ratio of batteries is low, which severely restricts both the speed and the range of the propulsion system.

lOne object of my invention is to provide an underwater propulsion system which leaves no wake.

Another object of my invention is to provide an underwater propulsion system having substantially no pumping loss in discharging exhaust products.

Still another object of my invention is to provide an -underwater propulsion system capable of operating at the extreme ocean depths.

A further object of my invention is to provide an underwater propulsion system having a liquid exhaust.

Other and further objects of my invention will appear from the following description.

In general my invention contemplates the provision of a fuel, comprising an alloy of sodium and potassium which is liquid at ocean temperatures, and an oxidizer comprising hydrogen peroxide, which is also a liquid, The reaction of the sodium-potassium alloy with the hydrogen peroxide is hypergolic, requiring no ignition apparatus. The reaction products are sodium hydroxide and potassium hydroxide. These reaction products are water soluble. This fuel-oxidizer combination is used to generate steam in a generally closed system. However, the system is partialily open and in equilibrium with sea water so that the heats of solution and the enthalpies of the hydroxides may be utilized. This open portion of the system comprises a solution chamber where sea water is evaporated to make up for water or steam losses in the closed system. The steam generated is delivered to a condensing turbine in a modified rankine cycle.

In the accompanying drawings which form part of the instant specification and whi-ch are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIGURE 1 shows a first embodiment of my invention in which make-up steam from the solution chamber is delivered to a mixed pressure turbine.

SZM Patented Feb. 7, 1967 FIGURE 2 shows a second embodiment of my invention in which make-up steam from the solution chamber is regeneratively employed for feed water heating.

In the following specification, the symbols (c), (l), and (g) respectively indicate solid, liquid, and gaseous states; and the symbol (aq x) indicates an aqueous solution in x mols of water.

Referring now more particularly to FIGURE 1 of the drawings, the oxidizer -comprises a stabile hydrogen peroxide aqueous solution which is stored in a container 3. The fuel comprises a sodium-potassium alloy which may conveniently be 50 atomic percent sodium and thus 37% sodium by weight. Such an alloy has a melting point of 25 C.=36.5 F. and is thus liquid even at low temperatures. However sea water temperatures of 28 F. have been reported. For such extremely low temperatures, the fuel may comprise 40 atomic percent sodium and thus contain 30% sodium by weight. This alloy has a melting point of -3.5 C.=26 F. and will be liquid at the very lowest sea water temperatures, As a fue-l, sodium is better than potassium because it has greater heating value per unit weight and because it has greater Weight lper unit volume (greater density). The alloy fuel th-us preferably contains the highest possible portion of sodium consonant with the required melting point. Tue liquid alloy fuel is stored in container 4. The oxidizer from container 3 is piped to the inlet of a positive displacement gear piurnp 5. The oxidizer at the outlet of vpump 5 is at a pressure appreciably above 700 p.s.i. and is piped to a spray nozzle '7 Within a catalytic decomposition chamber 8. The liquid oxidizer is accelerated through the spray nozzle 7 where it is discharged within chamber 8 at a pressure of 70() p.s.i. as a high velocity atomized spray of small droplets. Chamber 8 contains one or more meshes or screens formed of silver which act as a catalyst, causing decomposition of the hydrogen peroxide oxidizer in accordance with the following exothermic reaction:

The heat of reaction would result in superheated steam at a partial pressure of 470 p.s.i. and in oxygen at a partial pressure `of 23() psi., both at a temperature of 1850 F., it the oxidizer were unstable H2O2. The silver screens have a melting point of 1760 F.; and such tcmperature in the decomposition chamber would result in loss of the catalyst. However, `for a stable 90% H202 aqueous solution, the heat of reaction results in superheated steam at a partial pressure of 500 p.s.i. and in oxygen at a `partial pressure of 200 p.s.i., both at a temperature of only 1370" F. This temperature is appreciably less than the melting point of the silver catalyst screens. The lhot gaseous mixture from decomposition chamber S is piped to a reaction chamber indicated generally by the reference numeral 11. The liquid alloy fuel in container 4 is piped to the inlet of a positive displacement gear pump 6. The liquid fuel at the outlet of the pump 6 is at a pressure appreciably above 700 p.s.i. and is piped to a spray nozzle 1d within the reaction chamber 11. The fuel is accelerated through spray nozzle 10 where it is discharged within chamber 11 at a pressure of 700 p.s.i. as a high velocity atomized spray of small droplets. Feed water at a pressure appreciably above 700 psi. is piped 3,o E to a spray nozzle 9 within reaction chamber 11. The feed Water is accelerated through spray nozzle 9 where it is discharged within chamber 11 at a pressure of 700 p.s.i. as a high velocity atomized spray of small droplets. The feed water from nozzle 9, the fuel from nozzle 10, and the hot gaseous mixture from decomposition chamber 8 combine in'accordance with the following exothermic reactions:

NaK(l)-l2H-.O(g) NaOH(I)-l-KOHUH-HZQQI) H2(g) +1/2O2(g)' H2O(g) The amount of feed water through spray nozzle 9 is such as to yield superheated steam at a pressure of 700 p.s.i. and a temperature of 1000 F. The melting point of sodium hydroxide is 605 F.; and the melting point of potassium hydroxide is 715 F. Thus the temperature within reaction chamber 11 is suiciently high that both of the hydroxides are liquid. The molten hydroxides fall under the action of gravity to the bottom of chamber 11 Where they pass through small apertures or perforations 12 into a solution chamber 30. The superheated steam from reaction chamber 11 flows through a three-pass separator, indicated generally by the reference numeral 13, where any residual liquid hydroxides are removed. Apertures or perforations 14 are provided at the lowermost portion of each of the three passes of separator 13 so that the liquid hydroxides may flow therethrough into the solution chamber 30. Solution chamber 30 is maintained at a pressure of 680 p.s.i. by means of a pressure transducer 34, the operation of which will be subsequently described in detail. Liquid hydroxides flow thro-ugh apertures 12 and 14 not only under the influence of gravity but also under the inuence of the 20 p.s.i. pressure differential. The .superheated steam from separator 13 is conducted to the inlet of a turbine 47 which drives a propeller 15. The eX- haust steam from turbine 47 is conducted to a condenser 16 which is provided with a hot well 23 for collecting the condensate. Sea water is conducted through an intake 17, which may be provided with a protective screen, to the inlet of a centrifugal pump 18. The outlet of pump 18 provides cooling water through a condenser tube 19 within condenser 16. The liquid within solution chamber 30 is maintained at a predetermined level by transducer 33, the action of which will be described subsequently in detail. The enthalpy of the hot hydroxides issuing from apertures 12 and 14 and the heats of solution of the hydroxides generate saturated steam within solution chamber 30. A perforated dry pipe 35 positioned above the liquid level within the solution chamber 30 provides a large surface for separating from the saturated steam any entrained droplets of sea water. The relatively dry steam from dry pipe 35 is conducted through a singlepass separator 37 to the inlet of a normally closed valve 39. Separator 37 is provided to ensure that substantially no droplets of sea water, containing sodium chloride and other salts, are present in the How of saturated steam. The outlet of valve 39 is coupled to turbine 47 one or more stages downstream of the initial inlet from separator 13. Turbine 47 is of the lmixed-pressure type. It is supplied with superheated steam at a pressure of 700 p.s.i. from separator 13 and with saturated steam at a pressure of 680 p.s.i. from solution chamber 30. The auxiliary steam from valve 39 should be coupled to turbine 47 at a point where the pressure within the turbine is less than 680 p.s.i., as ifor example 660 p.s.i. Sea water is conducted through an intake 29, which `may be also provided with a protective screen, to the inlet of a positive displacement gear pump 28. I provide a counterflow heat exchanger comprising a heater 27 and a cooler 26. Sea water issuing from the outlet of pump 28 is conducted to the inlet of heater 27 and thence, from the outlet thereof, to solution chamber 30. Sea water from solution chamber 30, containing the sodium and potassium hydroxides in solution, passes to the inlet of cooler 26 and thence, from the outlet thereof, to the inlet of a positive displacement gear .pump 40. The hydroxide solution from the outlet of pump 40 is combined with the cooling water flowing through condenser tube 19 in a mixing chamber and overboard discharge duct 42. The con.- densate from hot well 23 is piped to the inlet of a positive displacement feed water gear pump 24. Feed water from the outlet of pump 24 flows through a counterflow heater element 25 associated with cooler 26. The outlet of heater 25 is coupled through a normally closed valve 46 to the outlet of heater 27. The outlet of heater 25 is also coupled through a submerged heat exchanger tube 32 within solution chamber 30 to spray nozzle 9. The submerged heat exchanger tube 32 is shunted by a normally closed valve 36 which is actuated by pressure transducer 34 to open position only if the pressure within the solution chamber 30 is less than 680 p.s.i. Hot well 23 is provided with a rst liquid level detector 20 and a second liquid level detector 22. Level detector 20 provides a signal opening valve 46 only if the liquid level within hot well 23 exceeds a certain desired value. Level detector 22 provides a signal opening valve 39 only if the liquid level within hot well 23 drops below the desired value. Gear pumps 5, 6, 24, and 40, Iand centrifugal pump 18 are all coupled to the turbine output shaft. The turbine output shaft is further connected to one side gear of a differential 45, the other 'side `gear of which drives gear pump 28. The spider of `differential is driven by a motor 44. The output of liquid level detector 33 is coupled to an amplifier 43 which drives servomotor 44 only when the liquid level within solution chamber 30 drops below the desired value. A oat valve 38 in the bottom of separator 37 `discharges sea water entrained in the saturated steam to the inlet of pump 40.

In operation of my propulsion system I shall assume a sea Wat-er temperature of F. and a temperature differential across the heat exchanger elements 26 and 27 of 50 F. Neglecting any ilow of saturated steam through valve 39, superheated steam at a pressure of 1000 F. and 700 p.s.i., having an enthalpy of 1514 B./lb. and an entropy of 1.70, expands through turbine 47 to a pressure of 4 p.s.i. It the expansion were isentropic, the turbine exhaust would have an enthalpy of 1037 B./lb., ya quality of and a `moisture content of 10%. Even this moisture would not produce appreciable blade erosion for the final stages of expansion. The isentropic work would be 477 B./lb. However for a turbine efciency of 81%, the actual work is 387 B./lb.; and the turbine exhaust has an enthalpy of 1127 B./lb. and an entropy of 1.86, and comprises saturated steam of quality. Such high quality exhaust is desirable since the presence of moisture decreases the turbine eHiciency. The saturated liquid at 4 p.s.i. in hot well 23 has a temperature of 153 F. and an enthalpy of 121 B./1b.

The over-all reaction is The heat of formation of the liquid sodium-potassium fuel comprises merely the heat of fusion absorbed during melting which is 0574-0631212 kg.cal. The heat evolved in the formation of H2O2 is 44.9 kg.-cal. Th-e heats evolved in the formations of NaOH and KOH in infinite `aqueous solution are respectively 112.2 and 115.0 kg.-cal. Thus the heat evolved in the over-all reaction is 183.6 kg.-cal. The heats evolved in the formation of NaOH(c) and KOH(c) are respectively 102.0 and 101.8 kg.-cal. Accordingly the heats of solution evolved in innite aqueous solution of NaOH and KOH are respectively and yielding a total of 23.4 kg.cal. The hydroxides flowing through apertures 12 and 14, however, are liquid at a ternperature of 1000 F. The heat evolved in the cooling of liquid sodium hydroxide from 1000 F. to its melting temperature of 605 F. is 4.2; the heat evolved in the fusion of liquid sodium hydroxide is 1.7; and the heat evolved in the cooling of the solid sodium hydroxide from 605 F. to 50 F. is 3.8 kg.-cal. The heat evolved in the cooling of the liquid potassium hydroxide from 1000 F. to its melting temperature of 715 F. is 3.2; the heat evolved in the fusion of liquid potassium hydroxide is 1.8; Iand the heat evolved inthe cooling of solid potassium hydroxide from 715 F. to 50 F. is 4.5 kg.-cal. The heat evolved in cooling the hydroxides from liquids at 1000 F. to solids at 50 F. is thus 19.2 kg.cal. The heat evolved in the cooling of the hydroxides and in their infinite aque-ous `solution is l9.2-l23.4=42.6 kg.cal. This means that of the heat released in the over-all reaction 183.6--42.6'=141.0 kg.cal. is evolved in reaction chamber 11.

If the counterllow heat exchanger comprising elements 26 and 27 had an efficiency of 100%, then the entire 42.6 kg.-cal. evolved externally of reaction chamber 11 could be utilized. However, I have assumed that a 50 F. drop exists across elements 26 and 27. This means that if the temperature of the sea water at the inlet of heater 27 is 50 F. then the temperature olf the hydroxide solution at the outlet of cooler 26 is 100 F. The loss in the heat exchanger comprising elements 26 and 27 is thus proportional to the extent of aqueous dilution of the hydroxides. The prob-lem is to determine the optimum aqueous dilution `-within chamber 30 such that the combined loss in the heat exchanger and 4of partial dilution is minimum. For example, assume the flow `of sea water through pump 28 is such as to produce, within chamber 30, NaOHtaq 3) and KOH(aq 3), evolving respective heats of formation of 108.9 and 111.8 kg.-cal. The loss in heat of solution of the sodium hydroxide is 112.2-108.9=3.3 l g.cal. The loss in heat of the solution of the potassium hydroxide is l15.0-11'1.8=3.2 kg.cal. The total loss in heat of the solution is 6.5 kg.-cal. Correspondingly the loss in the counterow exchanger for the required six moles of water is 3.0 kg.cal. This yields an exhaust loss olf 6.5-{3.0=9.5 lig-cal. Now assume that the tlow of `water through .pump 28 is increased to produce within chamber 30 NaOH(aq 6) and KOI-Haq 5) evolving respective heats of formation of 111.5 and 113.3 kg.cal. The loss in heat of the solution ofthe sodium hydroxide is 112.2-1ll.5= 0.7 kg.cal. The loss in heat of solution of the potassium hydroxide is 115.0-113.3=1.7 kg.cal. The total loss in heat of the solution is 2.4 kg.cal. Correspondingly the heat loss in the countertlow exchanger for the required eleven moles of water is 5.5 kg.cal. This yields an exhaust -loss of 2.4-l-5.5=7.9 kg.-cal. It will be noted that in going to the higher dilution within chamber 30, the

decrease in loss of heat of solution is greater than the increase in lo-ss in the counterow exchanger so that the total loss is decreased. It will be appreciated that if the temperature drop across the counterflow exchanger is larger than 50 F. then the exhaust loss will be minimum at lesser dilutions, while if the temperature drop across the counterflow exchanger is less than 50 F., then the minimum exhaust loss `will occur at greater dilutions. It will be appreciated that it is desired to hold the weight and bulk of the counterow exchanger to a minimum and further that, for a given size, the temperature drop across the exchanger increases with the rate of flow and hence with the amount of dilution.

In addition to the foregoing exhaust losses which are minimum for a certain dilution, `there is a further exhaust loss which is independent of the amount of dilution, assuming a xed temperature drop across the counterflow exchanger. This additional loss occurs because the hydroxides are 4discharged from cooler 26 at a temperature ot 100 F. instead of 50 F. This loss is equivalent to the heat involved in changing the temperature of NaOH( c) and KOH(c) by 50 F. which is 0.7 kg.-cal. The overall exhaust loss in discharging NaOH(rzq 6) and KOH(aq '5) at 100 F. is 7.9-|-0.7=8.6 kg.cal. Thus the useful heat available externally of reaction chamber 11 is 42.6-8.6=34.0 kg.-cal. The useful heat in the 6 over-all reaction is 183.6-8.6=l41.0l34.0=175.0 kg.- cal./mole of reactants. The total heat added to the feed water in producing superhated Steam is 1514-l21=1393 B./lb.=775 kg.cal./kg. of water.

Thus 175.0/775=.225 kg.=226 grams of water are circulated for each mole of reactants Consumed. The weight of one mole of 50 atomic percent Nal( fuel is 23|39=62 grams. The weight of one mole of a 90% H2O2 aqueous solution is 34 grams H2O2 plus 34/9=3.8 grams H2O yielding an oxidizer solution weight of 37.8 grams. The total weight of one mole of reactants is 99.8 grams. Hence 226/99.8=2.27 grams of water are circulated for each gram of reactants consumed.

The increase in enthalpy of the feed Water from pump 24 in passing through heaters 25 and 32 is (S40/175.0) 13932271 B./lb.

Accordingly the enthalpy of the compressed water at the inlet of spray nozzle 9 is 12l-l271=392 B./lb.; and the temperature is 415 F. The saturated water in equilibrium with the saturated steam in solution chamber 30 at a pressure of 680 p.s.i. have a temperature of 500 F. The minimum temperature differential between the saturated liquid in solution chamber 30 and. the compressed feed water in heater 32 is thus 85 F.

The hydroxide solution flowing through element 26 is cooled through 400 F. from 500 F. to 100 F. The sea water flowing through element 27 is heated through 400 F. from 50 F. to 450 F. It will be noted, however, that the mass rate of flow through cooler 26 is larger than that through heater 27 because of the presence of the dissolved hydroxides. The specic heat of the hydroxide solution is greater than that of raw sea water. The heat absorbed in heating eleven moles of water in element 27 through each 100 F. is 11.0 kg.-cal. The heat evolved in cooling solid hydroxides through each F. is 1.4 kg.cal. Accordingly the heat evolved in cooling the hydroxide solution in element 26 through each 100 F. is 11.0-l-1.4=12.4 kg.-cal. The heating of raw sea water in element 27 through 100 F. requires a change in temperature of the hydroxide solution of only The heat evolved in cooling solid hydroxides from 500 F. to 100 F. is 5.6 kg.cal. It is the purpose of element 25 to extract this heat from the hydroxide solution and add it to the feed water. The heat added to the feed water by heater 25 is Accordingly the enthalpy of the feed water at the outlet of heater 25 is 121-|45=l66 B./lb.; and the temperature of the compressed water is 198 F.

Counterilow exchanger elements 26 and 27 may each comprise four passes as shown, each pass of which produces a 100 F. rise in the temperature of the raw sea water flowing through element 27. The inlet of heater 25 is connected to cooler 26 at a point one pass prior to its outlet; and the outlet of heater 25 is connected to cooler 26 at a point one pass subsequent to its inlet. Thus at a point one pass removed from the high temperature ends of elements 26 and 27, the temperature of the raw sea water in element 27 is 450-100=350 F.; and the temperature of the hydroxide solution in element 26 is 500-89=411 F.; and the temperature of the feed water in element 25 is 198 F. Furthermore, at a point one pass removed from the low temperature end of elements 26 and 27 the temperature of the raw sea water in element 27 is 50 +l00=150 F.; the temperature of the hydroxide solution in element 26 is 100-l-89=l89 F.; and the temperature of the feed water in element 25 is 153 F. It will be noted that at the point one pass removed from the low temperature end of elements 26 and 27 the temperature differential is 189-150=39 F. whereas at a point one pass removed from the high temperature end of elements 26 and 27 the temperature differential is 4l1350z61 F. Thus in elements 26 and 27 there does exist a small variation of i 11 F. from an average 50 F. temperature differential at corresponding points. It will be further noted that at the point one pass removed from the low temperature end of element 26, the temperature differential for heating the feed water in element 2S is 189-153=36 F. while at a point one pass removed from the high temperature end of element 26 the temperature differential for heating the feed water in element 25 is 4ll-198=2l3 F. The heat added to the feed water in heater 32 is 34.0-5.6:28.4 kg.-cal.; and the corresponding increase in enthalpy of the feed water in heater 32 is 271-451226 B./lb.

Gear pumps 28 and 40 may be identical and, with servomotor 44 stationary, should 'be driven at identical speeds. If the openating depth is such that the external pressure is less than 680 p.s.i., then device 28 acts as an hydraulic pump absorbing shaft power and device 40 acts as an hydraulic motor generating shaft power. Because of leakage in devices 28 and 40, the liquid level in solution chamber 30 will tend to decrease. Detector 33 provides a signal of a certain polarity through amplifier 43 to :motor 44 causing rotation in such sense as to increase the rotational speed of pump 28. This requires power from motor 44 since the shaft power absorbed by pump 28` is increased.

If the operating depth is such that the external pressure is greater than 680 p.s.i., then device 28 acts as an hydra-ulic motor generating shaft power and device 40 acts as an hydraulic pump absorbing shaft power. Because of the leakage in devices 28 and 40, the liquid level in solution chamber 30 will tend to increase. Transducer 33 provides an opposite polarity signal which causes rotation of -motor 44 in an opposite sense, reducing the rotational speed of device 28 and its power output. The rotational speed and -power output of that side gear of differential 45 connected to the `turbine output shaft remain constant. This again requires power from servomotor 44. Thus although external pressures less than or greater than 680 p.s.i. cause a change in the direction of rotation of servomotor 44, the simultaneous reversal of the torque of device 2S when acting either as a pump or a motor always requires power from servomotor 44 in maintaining constant the liquid level within the solution chamber 30.

Solution chamber 30 is in essence a Iboiler; and its pressure is determined by the balance between the heat added `by the dissolving of the hot molten hydroxides and the heat extracted by exchanger 32. lf the pressure within solution chamber 30 is less than 680L p.s.i. then transducer 34 opens valve 36 so that most of the feed water (as 4for example 90%) by-passes element 32, appreciably reducing the heat extracted yfrom. the solution chamber. Accordingly, the temperature and hence the pressure within the chamber will rise. lf the pressure w-ithin the solution chamber 30 is greater than 680 psi., then transducer 34 permits valve 36y to return to its normally closed position; and all of the feed water passes through element 32. This increases the temperature of the feed water at the inlet of spray nozzle 9 appreciably above 415 F.; and the resultant cooling of the liquid within the solution chamber reduces its temperature and pressure.

Within reaction chamber 11, in the presence of water, one or more of the following reactions may occur:

NaOHQNaOH'MHZO) (n=l/2, 2/3, 3/4, 1, 7/2, 4)

KOH KOH/c(H2O) (k=1/2, 3/4, l, 2, 7)

This means that the hydroxides may be partially hydrated in the reaction chamber. Such partially lhydrated hydroxides passing through apertures 12 and 13 would remove some water from` the closed system. Further water may be lost by leakage. Some water is added to the closed system by virtue that the hydrogen peroxide oxidizer is in aqueous solution containing 10% by weight of water. Whether the net amount of water retained in the closed system increases or decreases depends upon the balance between water added by the oxidizer solution and water lost yby leakage and through partial hydration of the hydroxides in the reaction chamber. lf there is a net loss of Water in the closed system` then liquid level detector 22 provides a signal partially opening valve 39. Saturated steam obtained from the sea water in chamber 30 is throttled through a 20 p.s.i. pressure drop from 680 p.s.i. to 660 p.s.i. where it combines with the main steam flow through turbine 47 from separator 13. If', on the other hand, there is a net gain of water in the closed system, level liquid transducer 20 provides a signal partially opening valve 46, permitting a fractional portion of the feed water from the outlet of heater 25 to be bled off and discharged into the solution chamber 30. Solution chamber 30 constitutes the open portion of the system where water of the closed system is in equilibrium with sea water to maintain constant the condensate level in hot well 23.

The direction of flow through heat exchange element 26 is constant irrespective of whether the external sea pressure is ygreater or less than 680 p.s.i. This flow produces a pressure drop of perhaps 20 p.s.i. across cooler 26 so that the pressure at the outlet of cooler 26 may be 660 psi. Float valve 38 normally sustains the 20 p.s.i. differential existing between separator 37 and the inlet of purmp 40. When valve 39 is partially opened in response to a 'decrease in the condensate level in hot Wcll 23 lby transducer 22, minor amounts of sea water entrained in the saturated steam will gradually `be collected in the bottom of separator 37 and delivered to float valve 38. When the liquid delivered to float valve 38 reaches a certain level, the valve opens and discharges any `further liquids collected from separator 37 to the inlet of pump 40.

Sea water contains 3.5% of dissolved salts of which 2.7% is sodium chloride, having a melting point of 1472 F. It will be appreciated that since the temperature within the reaction and separator chambers 11 and 13 is only 1000 F., any sodium chloride dissolved in the feed water flowing through nozzle 9 would be deposited in solid form and would ultimately clog passages 12 and 14. It will be further appreciated that this problem will exist unless the temperature within the reaction chamber is increased above 1500 F. However such high temperatures create problems of turbine design and construction, Dry pipe 35 and separator 37 are provided to reduce the entrainment of salt-containing sea water to a minimum. Furthermore, saturated steam from solution chamber 30 flows through valve 39 only in order to make up for a net water loss in the closed system. The major portion of the heat provided in solution chamber 30 is extracted, not by the generation of saturated steam, but instead by the cooling effect of the regeneratively heated feed water flowing through exchanger 32.

Referring now to FIGURE 2, the system is substantially the same as that shown in FIGURE 1, except for a few modifications. Turbine 47a is of a standard singlepressure type in that it is supplied only with steam at a pressure of 700 p.s.i. from separator 13. I provide a differential pressure transducer 34a which responds to the difference between the pressure existing within reaction chamber 11 and the pressure existing within solution chamber 30. Differential pressure transducer 34a provides an output signal which opens valve 36 only if the differential pressure is greater than 20 p.s.i. Positive displacement gear pump 28 is directly driven by the turbine output shaft. The turbine output shaft is also coupled to one side gear of a differential a, the spider of which is again driven by the output shaft of servomotor 44. The other side gear of differential 45a drives positive displacement gear pump 40. The turbine output shaft is also coupled to one side gear of a differential 55, the other side gear of which drives a rst feed water pump 24a. The spider of differential 55 is coupled to an electromagnetic clutch 54. The outlet of heater 25 is coupled to a mixing chamber 52 which is provided with a pressure transducer 53. Transducer 53 energizes clutch 54 if the pressure within mixing chamber 52 drops below a `certain pressure which is appreciably greater than 11 p.s.i. but appreciably less than 680 p.s.i. The feed water flowing from the outlet of mixing chamber 52 is then raised to its nal pressure somewhat greater than 700 p.s.i. by a secondfeed water pump 56 which is driven by the output shaft of turbine 47a. The outlet of valve 39 is supplied to mixing chamber 52 rather than to the turbine.

In operation of the propulsion system of FIGURE 2, if there is a net loss of water in the closed system, saturated steam from solution chamber 30 is throttled through valve 39 and delivered to mixing chamber 52; and its heat is employed for regeneratively heating the feed water.

In FIGURE l the make-up steam from solution charnber 30 delivered to turbine 47 is merely saturated and not superheated. This results in a lower quality turbine exhaust having a higher moisture content and hence in a lower turbine efficiency. In FIGURE 2 the entire heat energy of the saturated steam delivered from solution chamber 30 is available for heating the feed water; and only superheated steam from separator 13 is delivered to turbine 47a, resulting in a higher turbine efficiency.

It will be recalled that the temperature of the feed water at the outlet of heater 25 is 198 F. The saturation pressure for this temperature is ll p.s.i. Additional heating of the feed water will result from the condensation in mixing chamber 52 of saturated steam from solution chamber 30. In order to ensure that the feed water is not converted to steam either in heater 25 or mixing chamber 52, I may provide a pressure within mixing chamber 52 of 300 p.s.i., corresponding to a saturation temperature of 417 F. The feed water in mixing chamber 52 will remain in a liquid state even if it were heated to 415 F. This could occur only if the entire heat evolved in solution chamber 30 were removed by the generation of saturated steam and no heat were removed by exchanger 32.

Feed water pump 24a should provide a volume rate of flow which is slightly larger (as for example than that of feed water pump 56. If the pressure within chamber 52 is less than 300 p.s.i. then transducer 53 fully energizes `clutch 54 so that the spider of differential 55 is stationary; and pump 24a delivers 10% more feed water to mixing chamber 52 than is removed by pump 56. This results in a rapid increase in the pressure within mixing chamber 52. Equilibrium is reached with clutch 44 only partially energized by transducer 53 so that of the shaft work supplied to the input side gear of differential 55, 90% is applied to pump 24a and 10% runs out through the spider where it is dissipated in clutch 54. A large pressure differential of p.s.i. exists across valve 39 so that irrespective of wide variations of pressure within solution chamber 30, saturated steam is throttled through valve 39 into mixing chamber 52.

I have shown an open feed water heater 52 since it has the greatest efficiency; but it does require the additional feed waterl pump 56. As will be appreciated by those skilled in the art I may instead employ a closed heater and deliver condensate from the closed heater to the condenser 16. In such event pump 56, transducer S3, clutch 54, and differential 55 may be eliminated; but the efficiency will be reduced.

It is the purpose of differential pressure transducer 34a to maintain a constant pressure differential to ensure the llow of liquid hydroxides through apertures 12 and 14 irrespective of pressure variations within the reaction chamber 11 and the solution chamber 30. The pressure within reaction chamber 11 is controlled by the ratio of the weight of the feed water supplied through nozzle 9 to the weight of reactants supplied through nozzles 8 and 10. As previously indicated, the ratio of weights is 2.26-to-1. The ratio is determined by the capacity and speed of pumps 5, 6, and 24 (FIG. 1) or 56 (FIG. 2). However, slight differential leakages may change the pressure within reaction chamber 11 from the desired pressure of 700 p.s.i.

Again gear pumps 28 and 40 may be identical and, with servomotor 44 stationary, should be driven at identical speeds. If the operating depth is such that the external pressure is greater than 680 p.s.i., then device 40 acts as an hydraulic pump absorbing shaft power. Because of leakage in devices 28 and 40 the liquid level in solution chamber 30 will tend to increase. Transducer 33 provides a signal of a certain polarity through amplifier 43 to servomotor 44 causing rotation in such sense as to increase the rotational speed of pump 40. This requires power from motor 44 since the shaft power absorbed by pump 40 is increased. If the operating depth is such that the external pressure is less than 680 p.s.i. then device 40 acts as an hydraulic motor supplying shaft power. Because of leakage in devices 28 and 40 the level in solution chamber 30 will tend to decrease. Transducer 33 provides an opposite polarity signal which causes rotation of motor 44 in an opposite sense, reducing the rotational speed of device 40. The reduction in power output of hydraulic motor 4l) requires an increase in the power output of servomotor 44 in order to maintain constant the power output of that side gear of differential 45a connected to the turbine shaft. Thus in FIGURE 2, as in FIGURE 1, servomotor 44 always provides power even though its direction of rotation may reverse for external pressure above or below 680 p.s.i. In FIGURES l and 2 it then makes little difference whether the differential drive is provided for pump 28 or for pump 40.

As will be appreciated by those ordinarily skilled in the art, the speed and capacity of pumps 5 and 6 should be properly selected to provide fuel and oxidizer in stoichiometric proportions. If excess oxidizer is supplied, then oxygen will build up in the system. It excess fuel is supplie-d, then hydrogen will build up in the system. As will be further appreciated by those skilled in the art, I may employ detectors for sensing the presence of oxygen or hydrogen in condenser 16 and operate a differential drive associated with either of gear pumps 5 or 6 so that the fuel and oxidizer will be delivered in the chemically correct proportions. The presence of oxygen is especially undesirable since oxidation of the high temperature turbine stages will occur unless they are formed of resistant materials. The presence of noncondensable gases such as oxygen or hydrogen in condenser 16 is inimical to its proper operation. As will be appreciated by those skilled in the art, suitable pumps or ejectors may be provided for removing these noncondensable gases and thus maintain the vacuum within the condenser.

Catalytic decomposition chamber 8 is provided to prevent an explosion upon initiation of the reaction. Assume for the moment that the liquid oxidizer were injected directly into reaction chamber 11 together with the fuel and feed water. The fuel would immediately react with the feed water, continuously releasing heat and hydrogen. However the oxidizer may not immediately decompose to liberate the oxygen which might then continuously react with the hydrogen. The build-up of hydrogen continues, accompanied both by a build-up in liquid oxidizer and by a rising temperature. The oxidizer will now violently decompose suddenly releasing the oxygen. The instantaneous reaction of large quantities of hydrogen and oxygen would result in an explosion. This problem arises because of the self-ignition lag of the liquid oxidizer. Decomposition chamber 8 insures that the oxidizer decomposes immediately upon injection so that no build-up of hydrogen and liquid oxidizer can occur. Furthermore the heat released in the decomposition chamber produces high temperature oxygen which readily reacts with the high temperature hydrogen. The presence of water (in gaseous form from the decomposed oxidizer and in liquid form from the feed water) acts as a catalyst insuring spontaneous reaction to completion of the hydrogen and oxygen.

As will be understood by those skilled in the art, the liquid sodium-potassium alloy fuel may be used merely to initiate the reaction. Once the reaction has stabilized and high temperatures prevail, then pure sodium fuel, which is normally a solid, may be heated to its melting temperature of 208 F. The pumping of alloy fuel is discontinued; and the reaction is continued by instead pumping the heated liquid sodium fuel into chamber 11. Rather than employing pure sodium as the primary fuel for continuing the reaction initiated by the alloy fuel, I may preferably use lithium. The solid lithium fuel is melted by heating to 357 F. so that it may be pumped into chamber 11. The lithium hydroxide solution in chamber 30 at a temperature of 500 F. may be employed for this purpose. Lithium hydroxide has a melting point of 833 F.; and is thus molten at the reaction chamber temperature of 1000 F. The heat evolved in the formation of lithium hydroxide in infinite aqueous solution is 121.5 kg.cal.; and lithium has an atomic weight of 6.94 grams. As a fuel, lithium is superior to sodium, since it has (Z3/6.94)(121.5/112.2)=3.6 times greater heating value per unit weight and, although its density is less, has about twice as much heating value per unit volume. The heat evolved in the formation of solid lithium hydroxide is 116.5 kg.cal.; and its heat of innite aqueous solution is 5.0 kg.-cal.

Two moles of lithium are required for each mole of hydrogen peroxide. The heat evolved in the over-all reaction with two moles of solid lithium at 50 F. is 198.1 kgfcal. The heat evolved in the cooling of two moles of lithium `hydroxide from a liquid at l000 F. to a solid at 50 F. is 17.7 kg.cal. The heat evolved in the infinite aqueous solution of two moles of lithium hydroxide is 10.0 kg.cal. The hot lithium hydroxide solution from chamber 30 is employed to heat two moles of solid I lithium slightly above its melting temperature which requires 1.6 kg.cal. The regenerative heating of the fuel increases the heat released in the reaction chamber and reduces the available heat externally thereof. The exhaust loss in discharging 2LiOI-I(aq 5.5) at 100 F., again requiring eleven moles of water, may be approximately 8.6 kg.-cal. The heat available externally of the reaction chamber is then 17.7-1-10.0-l.68.6=17.5 kg.cal. The useful heat in the over-all reaction is kg.-Cal per formula weight of reactants. The formula weight of reactants, including two moles of lithium, is 51.7 grams; and 244 grams of feed water are circulated for each gram formula weight of reactants consumed. Thus 4.73 grams of feed water are circulated for each gram of reactants consumed. The increase in enthalpy of feed water in passing through heaters 25 and 32 is 129 B./lb. The enthalpy of the water at the inlet of nozzle 9 is 250 B./lb.; and its temperature is 281 F. The increase in enthalpy of the feed water in heater 25 is 4l B./lb. The enthalpy of the feed water at the outlet of heater 25 is 162 B./lb.; and its temperature is 194 F. The increase of the enthalpy of the feed water in heater 32 is thus 88 B./lb. Within the reaction chamber the CII molten lithium hydroxide may be partially hydrated in one or more of the following reactions As will be appreciated by those skilled in the art, the oxidizer may be liquid oxygen rather than hydrogen peroxide. In such event no pump is required since the evolution of gaseous oxygen at the reaction chamber pressure may be controlled by varying the wattage input to an electrical immersion heater. However, with a liquid oxygen oxidizer there is a constant loss of one mole of feed water for each mole of NaK alloy or each two moles of either sodium or lithium fuel. This requires that large quantities of saturated steam be evaporated from solution chamber 30. Due to the inevitable entrainment of saltbearing sea water, the temperature within reaction chamber 11 may be increased to at least 1500" F. to prevent solid deposits from clogging apertures 12 and 14. Concomitantly turbine 47 or 47a should be formed of materials which retain their strength at these temperatures and which also resist oxidation. The reaction chamber temperature may however be maintained at 1000 F. by employing high-efficiency centrifugal separators.

It will be seen that I have accomplished the objects of my invention. My underwater propulsion system leaves no visible gaseous wake since the exhaust is liquid. Substantially no pumping loss is incurred in discharing the exhaust products since the shaft work either absorbed or generated by hydraulic device 28 is substantially equal to that either generated or absorbed by hydraulic device 40. My underwater propulsion system is capable of operating at the greatest ocean depths with substantially the same efficiency as at the ocean surface.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details Awithin the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, what I claim is:

1. An underwater propulsion system including in combination an oxidizer comprising hydrogen peroxide, means for decomposing the oxidizer, means for reacting the decomposed oxidizer and one of the three lightest alkali metals in the presence of water to produce steam, and means for expanding the steam to produce work.

2. An underwater propulsion system including in combination an oxidizer comprising hydrogen peroxide, means for catalytically decomposing the oxidizer, means for reacting the decomposed oxidizer and one of the three lightest alkali metals in the presence of water to produce steam, and means for expanding the steam to pro-duce work.

3. An underwater propulsion system including in combination an oxidizer comprising hydrogen peroxide in aqueous solution, means for decomposing the oxidizer, means for reacting the decomposed oxidizer and one of the three lightest alkali metals to produce steam, and means for expanding the steam to produce work.

4. An underwater propulsion system including in combination a liquid sodium-potassium alloy fuel which is fluid at ambient water temperature, means for reacting the fuel and oxygen in the presence of water to produce steam, and means for expanding the steam to produce work.

5. An underwater propulsion system including in combination a liquid sodium-potassium alloy fuel comprising not less than thirty percent by weight of sodium, means for reacting the fuel and oxygen in the presence of water to produce steam, and means for expanding the steam to produce work.

6. An `underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce superheated steam and a hydroxide of the metal, means for separating the hydroxide from the steam, means for expanding the separated steam to produce work, a chamber, means for delivering ambient water and the separated hydroxide into the chamber to produce a solution evolving heat, and means for utilizing the heat evolved in the solution chamber.

7. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce superheated steam and a hydroxide of the metal, a chamber, means for delivering ambient water and the hydroxide into the chamber to produce a solution evolving saturated steam, and means for expanding the superheated steam and the saturated steam to produce work.

8. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce superheated steam and a hydroxide of the metal, a chamber, means for delivering ambient water and the hydroxide into the chamber to produce a solution evolving saturated steam, means for expanding the superheated steam to produce work, means for condensing the expanded steam to produce feed water, means utilizing the saturated steam for regeneratively heating the feed water, and means for delivering the heated feed water to the reacting means.

9. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce steam and a hydroxide of the metal, a chamber, means for delivering ambient water and the hydroxide into the chamber to product a solution evolving heat, a heat exchanging element within the chamber, means for expanding the steam to produce work, means for condensing the expanded steam to produce feed water, and means for delivering the feed water through the element to the reacting means.

10. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce steam and a hydroxide of the metal, a chamber, means for delivering ambient water and the hydroxide into the chamber to product a solution evolving heat, a heat exchanging element within the chamber means for expanding the steam to produce work, means for condensing the expanded steam to produce feed water, means for delivering a first portion of the feed water to the reacting means, and means for delivering a second portion of the feed water through the element to the reacting means.

11. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce steam and a hydroxide of the metal, a cham ber, a counterow heat exchanger comprising a heater and a cooler, means for delivering ambient water through the heater to the chamber, means for delivering the hydroxide into the chamber to produce a solution, means for exhausting the solution from the chamber through the cooler, and means for expanding the steam to produce work.

12. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce steam and a hydroxide of the metal, a chamber, a counterflow heat exchanger comprising a cooler and a main heater and an auxiliary heater, means for delivering ambient water through the main heater to the chamber, means for delivering the hydroxide into the chamber to produce a solution, means for exhausting the solution from the chamber through the cooler, means for expanding the steam to produce work, means for condensing the expanded steam to produce feed water, and means for delivering the feed water through the auxiliary heater to the reacting means.

13. An underwater propulsion system including a combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce steam and a hydroxide of the metal, means for expanding the steam to produce work, means for condensing the expanded steam to produce feed water, a chamber, means for delivering ambient water and the hydroxide and a minor portion of the feed water into the chamber to produce a solution, means for exhausting the solution from the chamber, and means for delivering a maior portion of the feed water to the reacting means.

14. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce superheated steam and a `hydroxide of the metal, a chamber, means for delivering ambient water and the hydroxide into the chamber to produce a solution evolving saturated steam, means for expanding the superheated steam to produce work, means for condensing the expanded steam and the saturated steam to produce feed water, and means for delivering the feed water to the reacting means.

15. An underwater propulsion .system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce superheated steam and a hydroxide of the metal, a chamber, means for delivering ambient water and the hydroxide into the chamber to produce a solution evolving wet steam having entrained droplets of the solution, means for separating the entrained droplets from the wet steam to produce saturated steam, means for expanding the superheated steam to produce work, means for condensing the expanded steam and the saturated steam to produce feed water, and means for delivering the feed water to the reacting means.

16. A propulsion system for operation beneath the surface of sea water including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of impure saltbearing feed water to produce superheated steam and a hydroxide of the metal and molten salt at a temperature exceeding its melting point, means for separating the hydroxide and molten salt from the steam, means for expanding the separated steam to produce work, a chamber, means for delivering sea water and the separated hydroxide and molten salt into the chamber to produce a solution evolving heat, and means for utilizing the heat evolved in the solution chamber.

17. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce steam and a hydroxide of the metal, a chamber, a first and a second positive displacement hydraulic device each capable of reversible operation as a pump and as a motor, means comprising the rst device for delivering ambient water to the chamber, means for delivering the hydroxide into the chamber to produce a solution, means comprising the second device for exhausting the solution from the chamber, means for governing the differential rate of fluid flow of the rst and second devices, and means for expanding the steam to produce work.

18. An underwater propulsion system including in combination means for reacting oxygen and one of the three lightest alkali metals in the presence of feed water to produce steam and a hydroxide of the metal, means for expanding the steam to produce work, a condenser provided with a heat exchanging element, means for delivering the expanded steam into the condenser to produce feed water, means for delivering feed water from the condenser to the reacting means, a first chamber, a second chamber, means for delivering ambient water and the hydroxide into the first chamber to produce a hot concentrated solution, means for delivering ambient 31 15 water through the element to the second chamber, and means for delivering the solution from the first chamber into the second chamber to produce a cool dilute eX- haust solution.

19, An underwater propulsion system including in combination an oxidizer comprising hydrogen peroxide, means for decomposing the oxidizer, means for reacting the decomposed oxidizer and a liquid sodium-potassium alloy in the presence of water to produce steam, and means for expanding the steam to produce work.

20. An underwater propulsion process including the steps of reacting a liquid fuel comprising a sodiumpotassium alloy with oxygen in the presence of Water to produce thermal energy, utilizing said energy to heat to P. Q3 meltingy temperature a solid fuel comprising one of the two lightest alkali metals, and reacting the molten solid fuel with oxygen in the presence of water.

References Cited by the Examiner UNITED STATES PATENTS 2,484,221 10/1949 Gulbransen 60-50 2,706,890 4/1955 Schmidt 60-50 2,955,917 10/1960 Roberts et al. 60-50 X 3,019,197 1/1962 Saunders 60-37 X 3,101,592 8/1963 Robertson et al. 114-1635 X EDGAR W. GEGGHEGAN, Primary Examiner. 

1. AN UNDERWATER PROPULSION SYSTEM INCLUDING IN COMBINATION AN OXIDIZER COMPRISING HYDROGEN PEROXIDE, MEANS FOR DECOMPOSING THE OXIDIZER, MEANSFOR REACTING THE DECOMPOSED OXIDIZER AND ONE OF THE THREE LIGHTEST ALKALI METALS IN THE PRESENCE OF WATER TO PRODUCE STEAM, AND MEANS FOR EXPANDING THE STEAM TO PRODUCE WORK. 